Systems, methods, and media for providing power to an hdmi source

ABSTRACT

Systems, methods, and media for providing power to an HDMI source are provided. In accordance with some implementations, methods for providing power to an HDMI source are provided, the methods comprising: providing an AC signal to an HPD line of an HDMI port; determining that an L-C circuit is present on the HPD line when applying the AC signal; and in response to determining that an L-C circuit is present on the HPD line, connecting a power source to an HDMI 5V line of the HDMI port. In some implementations, the AC signal is a 231 kHz waveform. In some implementations, the AC signal is generated using a clock output. In some implementations, the methods further comprise integrating the clock output to provide the AC signal. In some implementations, the methods further comprise switching the frequency of the AC signal.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/014,633, filed Jun. 19, 2014, which is herebyincorporated by reference herein in its entirety.

BACKGROUND

With recent advances in video and graphics rendering and communicationshas come source media devices (hereinafter, each an “HDMI source”) thatare capable of plugging into an HDMI port of a sink media device(hereinafter, an “HDMI sink”) such as a television or monitor.

Currently, simple HDMI sources use external power supplies to providepower to those sources because the HDMI specification does not providefor an HDMI sink (such as a television) to provide power to the HDMIsource through its HDMI connector. Avoiding using an external powersupply may be desirable for a variety of reasons, such as cost and easeof use.

SUMMARY

Systems, methods, and media for providing power to an HDMI source areprovided. In accordance with some implementations, methods for providingpower to an HDMI source are provided, the methods comprising: providingan AC signal to an HPD line of an HDMI port; determining that an L-Ccircuit is present on the HPD line when applying the AC signal; and inresponse to determining that an L-C circuit is present on the HPD line,connecting a power source to an HDMI 5V line of the HDMI port. In someimplementations, the AC signal is a 231 kHz waveform. In someimplementations, the AC signal is generated using a clock output. Insome implementations, the methods further comprise integrating the clockoutput to provide the AC signal. In some implementations, the methodsfurther comprise switching the frequency of the AC signal. Inimplementations, determining that an L-C circuit is present on the HPDline comprises determining whether the AC signal is resonating in theL-C circuit. In some implementations, the methods further comprise:detecting a value of an HPD line of an HDMI sink; and providing thevalue to an HPD line of an HDMI source. In some implementation, themethods further comprise: determining that an L-C circuit is not presenton the HPD line when applying the AC signal; and in response todetermining that an L-C circuit is not present on the HPD line,disconnecting a power source from an HDMI 5V line of the HDMI port.

In accordance with some implementations, circuits for providing power toan HDMI source are provided, the circuits comprising: a microcontrollerconfigured to: provide an AC signal to an HPD line of an HDMI port;determine that an L-C circuit is present on the HPD line when applyingthe AC signal; and in response to determining that an L-C circuit ispresent on the HPD line, connect a power source to an HDMI 5V line ofthe HDMI port. In some implementations, the AC signal is a 231 kHzwaveform. In some implementations, the AC signal is generating using aclock output of the microcontroller. In some implementations, thecircuits further comprise an integrator coupled to the clock outputwhich integrates to the clock output to provide the AC signal. In someimplementations, the microcontroller also switches the frequency of theAC signal. In some implementations, determining that an L-C circuit ispresent on the HPD line comprises determining whether the AC signal isresonating in the L-C circuit. In some implementations, themicrocontroller also: detects a value of an HPD line of an HDMI sink;and provides the value to an HPD line of an HDMI source. In someimplementations, the microcontroller also: determines that an L-Ccircuit is not present on the HPD line when applying the AC signal; andin response to determining that an L-C circuit is not present on the HPDline, disconnects a power source from an HDMI 5V line of the HDMI port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a block diagram of hardware for detecting anHDMI source and providing power to the HDMI source in accordance withsome implementations.

FIG. 2 is an example of a schematic diagram of a circuit for detectingan HDMI source and providing power to the HDMI source in accordance withsome implementations.

FIG. 3 is an example of a more detailed schematic diagram of a circuitfor detecting an HDMI source and providing power to the HDMI source inaccordance with some implementations.

FIGS. 4A-4C together show an example of instructions that can beexecuted in a microcontroller (or other suitable device) for detectingan HDMI source and providing power to the HDMI source in accordance withsome implementations.

DETAILED DESCRIPTION

In accordance with some implementations, mechanisms are provided fordetecting if an HDMI source is connected to an HDMI port and, if yes,providing power through the HDMI port (e.g., using pin 18 of the port'sHDMI connector, which is normally used by a TV to detect the presence ofan HDMI source).

An example 100 of a mechanism in accordance with some implementations isshown in FIG. 1. As illustrated, mechanism 100 can be implemented as adetection module 102 that is present between an HDMI sink 104 and anHDMI source 106. In some implementations, the detection module uses apresence line 110 (e.g., an “HPD” line) of a port 108 to detect thepresence of the HDMI source by applying a low voltage stimulus (e.g.,which may be harmless to an unpowered source) to determine if a resonantL-C circuit 112 of the HDMI source can be detected. When the resonantL-C circuit of the HDMI source has been detected, the detection modulemay then apply a supply voltage (e.g., a 5V supply voltage via a“permanent 5V” line 114) to a supply voltage line 116 (e.g., an “HDMI5V” line). The sink in turn may set presence line 110 (e.g., the “HPD”line) active high and the detection module may then propagate the activehigh signal to the source.

Although detection module 102 of FIG. 1 is illustrated as being locatedbetween a port of HDMI source 106 and HDMI sink 104, the detectionmodule can be integrated with or can be part of HDMI sink 104 in someimplementations so that the port of the HDMI sink is port 108 in someimplementations.

The detection module may then continuously or periodically probepresence line 110 (e.g., the “HPD” line) to detect the removal of theHDMI source, in which case the detection module may disconnect thesupply voltage (e.g., from the “permanent 5V” line) from supply voltageline 116 (e.g., the “HDMI 5V” line).

FIG. 2 shows an example of an analog front end of a detection circuitthat is part of an HDMI sink in area 202 and an example of a resonantL-C circuit to be detected in area 204, in accordance with someimplementations.

The voltage sources V1 and V2 in FIG. 2 represent general purposeoutputs (GPOs) of a microcontroller (or other suitable device(s)) andthe active low signal OEMDET# can be used to inform the microcontroller(or other suitable device(s)) when the L-C circuit has been detected.

The voltage source VCC represents a 3.3V power supply (or any othersuitable power supply) of the analog front end (which can also be usedto power a microcontroller (or other suitable device(s)) (not shown) ifdesired).

The HDMI sink detects the HDMI source by detecting the presence of aresonant L1-C3 circuit in the HDMI source. The resonant frequency can bedetermined by L1 and the equivalent capacitance (Ceq) of C1, C2, and C3in series (e.g., as shown in the example of FIG. 2, L1 can be 100 μH,Ceq can be 4.76 nF, and the resonant frequency can be 231 kHz, in someimplementations). In this example, when the HDMI source is notconnected, the waveform on the HPD line can be triangular at 231 kHzwith a peak-peak value of 340 mV centered around 0V. This signal can begenerated by driving the integrator circuit R1-C1 with a 0V-3.3V 231 kHzsquare wave from the GPO V1.

When the HDMI source is connected, the circuit in the example of FIG. 2resonates at 231 kHz and the amplitude of the waveform on HPD line is asine wave with a peak-peak amplitude of:

${{898\mspace{14mu} {mV}} = \frac{3.3\mspace{14mu} {V \cdot H}\; {1 \cdot G \cdot R_{eq}}}{{{G^{2} \cdot R}\; 1} + R_{eq}}},{{wherein}\text{:}}$G = 1 + C 1/C 2 = 2;$Q = {\frac{{\omega \cdot L}\; 1}{R_{S}} = {\frac{{{2 \cdot \pi \cdot 231}\mspace{14mu} {{kHz} \cdot 100}\mspace{20mu} {µH}}\mspace{11mu}}{20\mspace{14mu} \Omega} = 7.25}}$R_(p) = R_(s) ⋅ (1 + Q²) = 1072  ΩReq = R 8//R2//R5//R_(p) = 480  Ω; and H 1 = 4/π = 1.27,

which is the 1st harmonic of a unity square wave.

It is assumed in the above calculations that (i) the serial resistanceR_(S) of the inductor is 2052, which takes into account the DCresistance, the core loss at 231 kHz and skin effect, and (ii)C3>>(C1·C2)/(C1+C2).

As shown, this signal is AC coupled by C4 to the 350 mV DC bias of Q1and turns on Q1 during the positive phase of the waveform (350 mV+898mV/2=799 mV). The R7-C5 circuit on the collector of Q1 filters theactive low signal OEMDET# which instructs the microcontroller (or othersuitable device) to apply HDMI 5V to the HDMI source (e.g., as shown inFIG. 1).

Because the detection signal is AC coupled to Q1, detection can beperformed when the HPD line is high or low (as driven by V2 at 0 or3.3V, for example); thus, the detection can be performed periodically todetect the removal of the HDMI source as well.

Although not shown in FIG. 2, any suitable circuit for connecting anddisconnecting a supply voltage (e.g., a 5V voltage) from the HDMI sinkto the HDMI source under the control of the microcontroller (or othersuitable device) can be provided in some implementations. For example, aswitch controlled by the microcontroller can be used to connect anddisconnect the supply voltage from the HDMI sink to the HDMI source.

Another example 300 of a circuit for implementing some implementationsof mechanisms disclosed herein is illustrated in FIG. 3. As shown,circuit 300 includes many of the same components as shown in FIG. 2. Forexample, the transistor, resistors, and capacitors shown in area 202 ofFIG. 2 are also shown in FIG. 3. The voltage sources V1 and V2 of FIG. 2are shown in FIG. 3 by two GPOs of microcontroller 308 (which can be anysuitable device (e.g., a hardware processor for controlling theoperation of the mechanisms described herein) such as anMSP430G2001IPW14 microcontroller available from Texas Instruments ofDallas, Tex.). The voltage source VCC of FIG. 2 is shown in FIG. 3 by a3.3V regulator 310 (which can be any suitable device for providingpower, such as a TLV70033 regulator available from Texas Instruments ofDallas, Tex.). Regulator 310 can receive power at its input from apermanent 5V source 302 (e.g., a USB port of a TV) or the HDMI 5V linebetween the source HDMI receptacle 304 and the sink HDMI receptacle 306,via diodes D1 (which can be any suitable diodes). A switch whichprovides power between the permanent 5V line and the HDMI 5V line(described above in connection with FIG. 1) can be provided bycontrollable switch 510 (which can be any suitable device forcontrolling a connection between a source of power and the HDMI 5V line,such as a TPS2051 switch available from Texas Instruments of Dallas,Tex.).

In accordance with some implementations, instructions that can beexecuted in a microcontroller (or other suitable device) in conjunctionwith the circuits of FIGS. 2 and 3 are illustrated in FIGS. 4A, 4B, and4C.

As shown, the instructions at lines 01-06 define a state variable ashaving one of three possible states (“idle,” “normal source,” and“power-over-HDMI source”) and set the state's initial value.

The instructions at lines 08-16 turn ON or OFF a GPO that controls aswitch that connects the permanent 5V line to the HDMI 5V line.

The instructions at lines 18-24 set the value on the HPD line at thesource connector as either a 0 or a 1.

The instructions at lines 26-28 determine a state of the HPD line at thesink connector.

The instructions at lines 30-33 return whether 5V is at the output ofthe switch (i.e., at the HDMI 5V line between the sink and the source).

The instructions at lines 34-36 check the signal of the collector oftransistor Q1 to determine whether an L-C circuit is detected.

The instructions at lines 38-51 apply a clock signal at differentfrequencies (e.g., 231 kHz, 231 kHz+3%, 231 kHz−3%, 231 kHz+6%, 231kHz−6%, . . . , 231 kHz+15%, 231 kHz−15%, and/or any other suitablefrequencies) to the HPD line to determine whether the L-C circuit can bedetected. As shown in these instructions, the clock signal can beprovided at different frequencies to account for tolerances in thecharacteristics of the inductor and the capacitor making up the L-Ccircuit.

The instructions at lines 52-80 form the main procedure of theinstructions and execute an infinite loop that perform three differentgroups of steps based on whether the process is in one of the threedifference states.

As shown, if the state is the idle state, the process:

-   -   a. turns off the 5V switch;    -   b. sets the HPD line at the source to match the HPD line at the        sink;    -   c. if 5V is on the HDMI 5V line, sets the state to the normal        source state;    -   d. if 5V is not on the HDMI 5V line and the HPD line is        connected to an L-C circuit, sets the state to a power-over-HDMI        source state; and    -   e. if 5V is not on the HDMI 5V line and the HPD line is not        connected to an L-C circuit, delays the process by one second        and leaves the state in the idle state.

If the state is in the normal source state, the process:

-   -   a. turns off the 5V switch;    -   b. sets the HPD line at the source to match the HPD line at the        sink; and    -   c. if the HDMI 5V line is not at 5V, sets the state to the idle        state.

If the state is in the power-over-HDMI source state, the process:

-   -   a. turns on the 5V switch;    -   b. sets the HPD line at the source to match the HPD line at the        sink;    -   c. if the HPD line is not connected to an L-C circuit, sets the        state to an idle state; and    -   d. if the HPD line is connected to an L-C circuit, delays the        process by one second and leaves the state in the        power-over-HDMI source state.

In some implementations, any suitable computer readable media can beused for storing instructions for performing the processes describedherein. For example, in some implementations, computer readable mediacan be transitory or non-transitory. For example, non-transitorycomputer readable media can include media such as magnetic media (suchas hard disks, floppy disks, etc.), optical media (such as compactdiscs, digital video discs, Blu-ray discs, etc.), semiconductor media(such as flash memory, electrically programmable read only memory(EPROM), electrically erasable programmable read only memory (EEPROM),etc.), any suitable media that is not fleeting or devoid of anysemblance of permanence during transmission, and/or any suitabletangible media. As another example, transitory computer readable mediacan include signals on networks, in wires, conductors, optical fibers,circuits, any suitable media that is fleeting and devoid of anysemblance of permanence during transmission, and/or any suitableintangible media.

The provision of the examples described herein (as well as clausesphrased as “such as,” “e.g.,” “including,” and the like) should not beinterpreted as limiting the claimed subject matter to the specificexamples; rather, the examples are intended to illustrate only some ofmany possible aspects.

Although the disclosed subject matter has been described and illustratedin the foregoing illustrative implementations, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter can be made without departing from the spirit and scopeof the disclosed subject matter, which is limited only by the claimsthat follow. Features of the disclosed implementations can be combinedand rearranged in various ways.

What is claimed is:
 1. A method for providing power to an HDMI source,comprising: providing an AC signal to an HPD line of an HDMI port;determining that an L-C circuit is present on the HPD line when applyingthe AC signal; and in response to determining that an L-C circuit ispresent on the HPD line, connecting a power source to an HDMI 5V line ofthe HDMI port.
 2. The method of claim 1, wherein the AC signal is a 231kHz waveform.
 3. The method of claim 2, wherein the AC signal isgenerating using a clock output.
 4. The method of claim 3, furthercomprising integrating the clock output to provide the AC signal.
 5. Themethod of claim 1, further comprising switching the frequency of the ACsignal.
 6. The method of claim 1, wherein determining that an L-Ccircuit is present on the HPD line comprises determining whether the ACsignal is resonating in the L-C circuit.
 7. The method of claim 1,further comprising: detecting a value of an HPD line of an HDMI sink;and providing the value to an HPD line of an HDMI source.
 8. The methodof claim 1, further comprising: determining that an L-C circuit is notpresent on the HPD line when applying the AC signal; and in response todetermining that an L-C circuit is not present on the HPD line,disconnecting a power source from an HDMI 5V line of the HDMI port.
 9. Acircuit for providing power to an HDMI source, comprising: amicrocontroller configured to: provide an AC signal to an HPD line of anHDMI port; determine that an L-C circuit is present on the HPD line whenapplying the AC signal; and in response to determining that an L-Ccircuit is present on the HPD line, connect a power source to an HDMI 5Vline of the HDMI port.
 10. The circuit of claim 9, wherein the AC signalis a 231 kHz waveform.
 11. The circuit of claim 10, wherein the ACsignal is generating using a clock output of the microcontroller. 12.The circuit of claim 11, further comprising an integrator coupled to theclock output which integrates to the clock output to provide the ACsignal.
 13. The circuit of claim 9, wherein the microcontroller alsoswitches the frequency of the AC signal.
 14. The method of claim 9,wherein determining that an L-C circuit is present on the HPD linecomprises determining whether the AC signal is resonating in the L-Ccircuit.
 15. The circuit of claim 9, wherein the microcontroller also:detects a value of an HPD line of an HDMI sink; and provides the valueto an HPD line of an HDMI source.
 16. The circuit of claim 9, whereinthe microcontroller also: determines that an L-C circuit is not presenton the HPD line when applying the AC signal; and in response todetermining that an L-C circuit is not present on the HPD line,disconnects a power source from an HDMI 5V line of the HDMI port.